Rotor blade folding mechanism



Aug. 30, )(961) H. E. LEMONT, JR

RoToR BLADE FOLDING MECHANISM F11ed.Aug. e, 195'? 3 Sheets-Sheet l l .o o- /3 l2 H INVENTUR HAROLD E. LEMONZJK Aug. 30, 1960 H. E. LEMONT, JR 2,950,767

ROTOR BLADE FOLDING MECHANISM Filed Aug. 6, 1957 3 Sheets-Sheet 2 INVENTOR HAROLD E. LEMONT Jr.

ATTORNEY Aug. 30, 1960 H. E. LEMONT, JR 2,950,767

ROTOR BLADE FDLDING MECHANISM Filed Aug. 6, 1957 3 Sheets-Sheet 3 INVENTOR HAROLD E. LEMONT, Jf.

- ATTORNEY p 2,950,767 Patented Aug. 30, 19d@ Boron BLADE FoLDlNG MECHANISM Harold E. Lemont, Jr., Avon, Conn., assigner, by mesne assignments, to Boeing Airplane Company, Seattle Wash., a corporation of Delaware Filed Aug. 6, 1957, ser. N0. 676,517

7 claims. (C1. 17o-160.12)

This invention relates to rotary wing aircraft and more particularly' to mechanism for folding the rotor blades thereof. A

The principal object of this invention is to provide means for folding the blades about a substantially vertical axis and/or about their lead-lag pivot. It is a further otherwise secured a drive -gear 28 which engages the gear 22 lixedly attached to the damper. By such arrangement, operation of the actuator 26 causes rotation of the damper 19 relative to the links 24 and 25. Link 25 is provided with an extension 29 which when the mechp anism is in the locked position shown in Fig. 1, is adapted object to provide folding mechanism which includes the g lead-lag damper whereby folding is accomplished without disconnecting the lead-lag damper :and without disconnecting the pitch control mechanism associated with the blades. It is a still further object to provide power means for actuating the folding mechanism whereby initial actuation thereof unlocks the folding mechanism and the blade may then 'be folded manually in either direction or continued operation of .the power means actuates the folding mechanism to fold the blade in one direction.

Other objects and advantages will become apparent from the following description when read in conjunction with the accompanying drawings in which:

Fig. 1 is a plan Yview showing the blade in the unfolded position and showing in phantom the position of the fold- Y ing Imechanism in unlocked position;

Fig. 2 is a plan view showing in'solid lines and in phantom respectively, Ithe blade and folding mechanism in the partially folded position when being folded in one direction, and when being folded in the opposite direction; Fig. 3 is a plan View showing in solid lines and in phantom, respectively, the blade and folding mechanism in folded position when folded in `one direction, and when folded in the opposite direction;

Fig. 4 is a side elevation of the blade folding mechanism of Fig. l;

Fig. 5 is a view taken along line- 5 5 of Fig. 2 showing the blade folding mechanism; and

Fig. 6 is an exploded view of a portion of the blade folding mechanism.

As shown in the drawings, numeral 11 indicates the root end of a rotor blade which is mounted by means of the lead-lag pivot or vertical pin 12 to a pitch bearing member 13 provided with a pitch arm 14 which at its outer extremity is connected to pitch control linkage not shown. The pitch bearing member 13 is mounted by means of a horizontal pin '15 to the rotor hub 16 which is iixedly attached to and rotated by the vertical drive shaft 17.

A bifurcated bracket member 18 is clamped or otheri wise secured to the root end of the blade and pivotally supports one end of a lead-lag damper y19. The other end of the damper is provided with ears 20 and 21, and as is more clearly shown in Fig. 6, the ear 21 has xedly attached thereto a gear 22. A pivot pin 23 extends through holes in the ears 20 and 21 and the `gear 22, and has attached at either end links 24 and 25. Link 24 is provided with an extension which forms a mounting plate for a reversible rotary actuator 26, preferably of the electrical type, and having a drive shaft 27 extending through the mounting plate and upon which is keyed or to bear against an abutment plate 30 provided on the housing of the pitch bearing 13.

The other ends of links 24.and 25 are pivotally connected to links 31 and 32 respectively, which in turn are pivotally connected to bracket members 33 and 34 xedly attached to the housing of the pitch bearing.

It will be noted that when the mechanism is in the locked position shown in Fig. l, the pivotal connections between links 24 and 31 and links 25 and 32 are overcenter with respect to the pivotal, connection of the damper to the bracket member 18 and the pivotal connections of the bracket members 33 and 34 to the respective links 31 and 32 whereby any compression or tension forces transmitted to the damper as a result of the lead-lag motion vof the blade tends to force extension 29 more tightly against the abutment plate 30. This action may be more clearly vunderstood by a description of the operation -of the blade folding mechanism of the present invention from the partially folded position shown in Fig. 2Y to the fully extended and Ilocked position shown in Fig. 1. In order to accomplish this change n position the power actuator 26 is operated to drive link 25l counterclockwi'se with respect to the pivotal connection between link 25 and link 19 Iuntil the advancing edge in the `direction of rotation of link 25 abuts the link 32 along the surface shown as a dotted line on the link 32 in Fig. 2. Continued operation of the actuator 26 driving link 25 counterclockwise with respect to link 19 will cause the pivotal connection between link 32 and link 25 to move in a counterclockwise direction since link 32 is caused to rotate about its pivotal connection with bracket member 34 as a result of the abut-ment of link 25 with link 32. This counterclockwise rotation is continued until extension 29 of link 25 contacts abutment plate 30 and at this extreme position the pivotal connection between link 32 and link 25 is in the overcenter position referred to above.

Operation of the actuator 26 is such as to rotate the damper 19 in a counterclockwise direction with respect to the links 24 and 25. Initial operation positions the linkage as shown in phantom in Fig. l. When in this position, the linkage is unlocked and the blade may be manually `folded in either direction to the positions shown in Fig. 3. However, continued operation of the actuator 26 continues to rotate the damper in a counterclockwise direction with respect to the links 24 and 25, whereby the linkage passes through the solid line position shown in Fig. 2 and inally to the solid line position shown in Fig. 3 wherein the blade is completely folded. Operation of the actuator 26 in .the reverse direction causes clockwise rotation of the damper 19 relative to the links 24 and 25 and hence an unfolding of the blade from the solid line position shown in Fig. 3 to that shown in Fig. l. Limit stops not shown may be provided for deenergizing the actuator 26 when the linkage has reached either of the' extreme positions.

Although shown and described in what is believed to be the most practical and preferred embodiment, it is apparent that departures therefrom will suggest themselves t-o those skilled in the art `and may be made without departing from the spirit and scope of the invention. I therefore do not wish to restrict myself to the particular form of construction illustrated and described, but desire to avail myself of all modifications that may fall within the scope of the appended claims.

Having thus described my invention, what I claim is: l. In combination with va rotor blade having a fixed portion and a folding portion pivotally connected thereto, a Vblade folding mechanism comprising a rst link pivotally connected to vsaid folding portion, a secondlink pivotally connected to'said xed portion, and -an intermediate link pivotally interconnecting said ti-rst and second links to form a three-link toggle combination operatively connected betweenssad foldingV portion `)and said fixed portion, abutment means'on said secondVY link for engagement with 'said intermediate link and power means Y ing about `a pivot joint, a blade folding mechanism comprising a iirst link pivotally connected to the blade at a pointoutboard of said pivot joint, a second link pivotally connected Yat a` point inboard of said pivot joint, an intermediatev link pivotally connected to said iirst.and;saidY second links to form therewith a three-linke toggle con- Y nection'disposed adjacent said pivot'joint, actuator means carried lbyone of said Ylinks andeadaptedtto positionsaid toggle connection between-locked and unlocked positions, and damper meansucontained within one of said links to restrain'motiorrofsaid blade about said pivot jointwhen vsaid toggle connection is in locked position. Y

4, in combination with a rotor vblade comprising a xed portion and a folding portion pivotal-ly connected to Ysaid fixed portion, a iirst link pivotally connected to said folding-(portion, a second link pivotally connected to said fixed portion, anV intermediate link pivotally Yconnected to said Erst vand said second links Vto form therewith a threelink toggle connection, abutment means provided on said fixed portion, and means provided on said intermediate YYlink for'engagement with said abutment Ymeans-.when

said blade is in the unfolded position, said pivotal -connection between said first Ilink and'said intermediate link being-positioned, when said Iblade is in the unfolded position, over-center with respect to the-pivotal connections between said rst vllink and said folding portionand beits pivotal connectionwith said fixed portion, abutment' .4 tween said second link and said iixed portion, and abutment means on said second link for engagement with said intermediate llink thereby limiting movement thereof, whereby said rotor blade is llocked in unfolded position. 5 In combination with a rotor blade comprising a fixed portion and :a Vfolding portion .pivotally connected thereto, a iirst link pivotally connected to said folding portion, a second link pivotally connected to said fixed portion, an intermediate link'pivotally connected to Ysaid first and said second linksto form therewith ai'three-link toggle connection, vdamper means V,contained within one of said links for restraining'rnotion of'said folding portion about means provided on said iixedportionand means provided on said intermediateY link for engagement with said abutment means, and actuator meansY carried by said Y intermediate link Aand Yadapted to cause rotation of said second and said intermediate links relative to one another. Y j Y Y l 6. The combination of. claim 5 and wherein said damper means is contained within said rst linkf7. In combination vwith a rotor blade having a fixed portion -and'a folding portion'pivotally connectedV thereto, a blade folding mechanism'comprising `a first link Vpivotally connected -to said folding portion, a second link pivotally connected Ito said fixed-portion, and an intermediate link-pivotally interconnecting said iirst and second links ytofform a three-'link toggle Ycombinationoperatively con nected between said folding portionY land said fixed portion, damper means contained within said first link for restraining 'motion of said folding portion about its pivotal connection with said fixed portion, and power means 'interacting between two of the links of said threelink toggle combination at their common pivotal connec- -tion for imparting motion to said links relative to each other, whereby'said folding vportion'is-pivotally moved relative to said fixed portion. Y

YReferences Cited in the Yfile'of this patent UNITED sTATns'PATETs Y 2,468,425 pompt-.mer Apr. 26, 1949 2,533,429 Carpenter. Dec. l2, 195.0 

